Sure enough, the problem that Colonel Fitzroy couldn't solve was immediately handled by Eld upon his arrival.
Eld took some red cloth from the ship and gifted it to them. The natives wrapped the red cloth around their necks right away, and then they became friends. The Tierra del Fuego people express friendliness by patting each other's chests and making a clucking sound, like when someone feeds chickens.
The elder first patted Eld, then walked over to me. After repeating this friendly gesture several times, he ended the ritual by vigorously patting my chest and back three times. Then he exposed his own chest, indicating for me to reciprocate. I mimicked the gesture, and he seemed particularly pleased.